An example of an information processing system, such as a cloud system, including a plurality of operation devices, which starts a standby operation device working when a fault occurs in a working operation device, is disclosed by the patent document 1 and the patent document 2.
A computer system described in the patent document 1 includes a first computer which processes transactions, a standby computer, a second computer and a third computer. The second computer includes a management unit which manages the first computer and the standby computer. The third computer manages starting and stopping of the standby computer. When a fault occurs in the first computer, the second computer controls the standby computer taking over the transactions from the first computer. The third computer determines whether a fault occurs in the second computer. When a fault occurs in the second computer, on the basis of acquired configuration information, the third computer controls the standby computer taking over the management unit from the second computer.
A cluster system described in the patent document 2 includes three or more nodes. Each node includes a cluster management unit which determines which the node is among a first node, a second node, and a third node. The first node executes an application. When a fault occurs in the first node, the second node executes the application. The third node is a node other than the first node and the second node. The second node synchronizes application information with that of the first node by a fully-synchronizing method. The cluster management units of the second node and the third node detect a fault occurs in the first node, respectively. When a fault occurs in the first node is detected, the second node works as the first node. Moreover, when the occurrence of the fault is detected in the first node, the cluster management unit of one of the third nodes determines changing to the second node. The third node whose cluster management unit determines changing to the second node works as the second node.
[Patent document 1] Japanese Patent Application Laid-Open No. 2010-067042
[Patent document 2] Japanese Patent Application Laid-Open No. 2012-185560